Sensor device and a method of manufacturing the same

ABSTRACT

A sensor device for analyzing fluidic samples is provided, wherein the sensor device comprises a stacked sensing arrangement comprising at least three sensing layers and a multilayer structure, wherein the multilayer structure has a hole formed therein which is adapted to let pass the fluidic sample and wherein the stacked sensing arrangement is formed in the multilayer structure in such a way that the fluidic sample passes the stacked sensing arrangement when the fluidic sample passes the hole.

FIELD OF THE INVENTION

The invention relates to a sensor device, in particular to a sensordevice for analyzing a fluidic sample.

Moreover, the invention relates to a method of manufacturing a sensordevice.

BACKGROUND OF THE INVENTION

A biosensor may be denoted as a device which may be used for thedetection of an analyte and may combine a biological component with aphysicochemical or physical detector component.

Rapid, reliable and inexpensive characterization of polymers,particularly nucleic acids, has become increasingly important. Ahigh-throughput device that can probe and directly read, at thesingle-molecule level, hybridization state, base stacking, and sequenceof a cell's key biopolymers such as DNA, RNA and even proteins, willdramatically alter the pace of biological development. For example, U.S.Pat. No. 5,795,782 discloses that a voltage bias could drivesingle-stranded charged polynucleotides through a 1-2 nanometertransmembrane channel in a lipid bilayer. Data in the form of variationsin channel ionic current provide insight into the characterization andstructure of biopolymers at the molecular and atomic levels. The passageof an individual strand through the channel could be observed as atransient decrease in ionic current. Experiments using biologicalmembranes and pores have demonstrated extraordinary electronicsensitivity to the structure of translocating molecules.

However, conventional methods and devices may still exhibit someproblems concerning the reliability of the characterizations ordistinguishing different components of a fluidic sample.

OBJECT AND SUMMARY OF THE INVENTION

Thus, there may be a need to provide a sensor device which may morereliable in distinguishing different components or portions of a fluidicsample or analyte, in particular of DNA bases of a DNA strand.

In order to meet the need defined above, a sensor device and a method ofmanufacturing a sensor device according to the independent claims areprovided. Additional enhancements are described in the dependent claims.

According to an exemplary aspect a sensor device for analyzing fluidicsamples is provided, wherein the sensor device comprises a stackedsensing arrangement comprising at least three sensing layers and amultilayer structure, wherein the multilayer structure has a hole formedtherein which is adapted to let pass the fluidic sample and wherein thestacked sensing arrangement is formed in the multilayer structure insuch a way that the fluidic sample passes the stacked sensingarrangement when the fluidic sample passes the hole.

In particular, the hole may be a nanopore having a circular orrectangular cross section, for example. The diameter or width of thenanopore may be less than 20 nm, in particular less than 10 nm, moreparticularly less than 5 nm, e.g. less than 2 nm. The hole may be athrough hole, e.g. a hole passing leading through the whole multilayerstructure. Thus, the hole may enable that the fluidic sample, e.g. ananalyt, flows through the hole and thus through the multilayerstructure. For example, the fluidic sample flowing through the hole mayform a separation between two portions of each sensing arrangement, i.e.one portion of each layer of the stacked sensing arrangement may bearranged on one side of the hole while the portion of each layer of thestacked sensing arrangement may be arranged on the opposite side of thehole, e.g. the layers or levels of the stacked sensing arrangement mayform a portion of a wall defining the hole, however the portions of eachlayer of the stacked sensing arrangement may be electrically insulatedwherein the hole and/or the fluidic sample may form a part of theelectric insulation between the two portions. Additionally, a sealinglayer may be provided which forms the sidewalls of the hole and whichinsulate the stacked sensing arrangement and the fluidic sample passingthrough the hole from each other.

According to an exemplary aspect a sensor array for analyzing a fluidicsample is provided, wherein the sensor array comprises a plurality ofsensor devices according to an exemplary aspect.

In particular, the plurality of sensor devices may be formed in a singlemultilayer structure comprises a plurality of holes each associated witha respective stacked sensing arrangement.

According to an exemplary aspect a method of manufacturing a stackedsensing arrangement for a sensor device for analyzing components offluidic sample is provided, wherein the method comprises providing amultilayer structure comprising a stacked sensing arrangement, andforming a hole through the stacked sensing arrangement, wherein the holeis adapted to let pass the fluidic sample. In particular, the forming ofthe hole may be performed by standard lithography techniques, e.g.etching. However, every suitable method may be used to form said hole,e.g. e-beam, ion-beam or the like. After forming of the hole, the holemay be modified or processed. For example, in some cases the size of thehole may be altered according to the needs. One possible alteration maybe to reduce the size by depositing or forming spacers on sidewalls ofthe hole. In particular, one or more layers of the multilayer structuremay form a stopping layer above or below the stacked sensingarrangement, which may be used for further processing steps, e.g. of anetching step or a polishing step. For example, the stacked sensingarrangement may comprise a plurality of sensing layers, i.e. layerswhich are adapted to measure signal indicative for a specificcharacteristic of the fluidic sample passing the sensing layer at thatpoint in time. According to a specific embodiment the sensing layer maybe a conductive layer.

The term “sensor array” may particularly denote an arrangement of aplurality of sensors or sensor devices for instance in a regularpattern, e.g. a matrix pattern. The number of sensors of such a sensorarray may be larger than two, particularly larger than ten, moreparticularly larger than one hundred.

The term “sensor device” may particularly denote any device which may beused for the detection of a fluidic sample or analyte. Examples forsensors which may be realized according to exemplary embodiments are gassensors, biosensors, pH sensors, humidity sensors, etc. According to anembodiment, a principle on which the sensor device is based on may be anelectric sensor principle which may detect the fluidic sample orparticles on the basis of an electric measurement, e.g. by using thestacked sensing arrangement.

The term “fluidic sample” may particularly denote any subset of thephases of matter. Such fluids may include liquids, gases, plasmas and,to some extent, solids, as well as mixtures thereof. Examples forfluidic samples are DNA containing fluids, cells containing fluids,blood, interstitial fluid in subcutaneous tissue, muscle or braintissue, urine or other body fluids. For instance, the fluidic sample maybe a biological substance. Such a substance may comprise proteins,polypeptides, nucleic acids, DNA strands, etc. Furthermore, the fluidicsample may comprise particles, e.g. molecules, organic molecules,biological particles, DNA, RNA, proteins, amino acids, beads,nano-beads, nano-tubes, etc., in particular biological particles, e.g.any particles which play a significant role in biology or in biologicalor biochemical procedures, such as genes, DNA, RNA, proteins, enzymes,cells, bacteria, virus, etc.

The term “sensing layer” may particularly denote a layer of materialable, alone or in combination with other sensing layers, to detect aspecific characteristic of the fluidic sample like electric, dielectric,magnetic or optic properties. The sensing layer may be made ofconductive material (Ta, TaN, Cu, Al, Ti, . . . ) or a combination ofconductive materials. The sensing layer may cover completely orpartially the multilayer structure. It may be patterned.

The term “stacked sensing arrangement” may particularly denote anarrangement of several sensing layers, e.g. at least three sensinglayers, wherein the sensing layers are arranged above each other andhaving a dielectric layer arranged in between electrically insulatingthe sensing layers so that multiple independent sensing arrangements maybe formed. The term “above of each other” may particularly denote thatthe stacked sensing arrangement may have a quasi two-dimensionalextension, i.e. the extension in two dimensions is much greater than inthe third one, and the sensing layers are stacked or piled up withrespect to the third direction, i.e. the direction having the smallextension. Each sensing layer may be adapted to perform an independentmeasurement of a specific characteristic of the passing fluidic sample,wherein the measurement may be based on electric, dielectric, magneticor optic properties of the fluidic sample or particles in the fluidicsample. A combination of sensing layers may be adapted to perform ameasurement of a specific characteristic of the passing fluidic sample,wherein the measurement may be based on electric, dielectric, magneticor optic properties of the fluidic sample or particles in the fluidicsample.

By providing a sensor device comprising a stacked sensing arrangement itmay be possible to perform multiple measurements for one and the samefluidic sample or analyt passing the stacked sensing arrangement. Thus,it may be possible to perform statistical and/or error cancellationtreatment afterwards since the fluidic sample, e.g. DNA, may faceseveral sensing layers one after the other in the hole or may face acombination of sensing layers. Furthermore, the use of a stacked sensingarrangement may enable the possibility to arrange the sensing layersclose to each other so that a good resolution may be achieved withrespect to the different components of the fluidic sample. Inparticular, an arrangement of the sensing layers may be enabled whichprovide the possibility that a sequential “reading” or analysis of thefluidic sample may be performed. For example, it may be possible to evendistinguish different DNA bases of a DNA strand, when the DNA strandpasses through the hole and thus through the stacked sensingarrangement. Additionally the use of a stacked sensing arrangement mayenable the implementation of several metal layers or levels in themultilayer structure so that an integrated circuit may be implemented aswell in the multilayer structure. For example, it may be possible tointegrate electronic components into the multilayer structure, e.g. anon-chip amplification or an on-chip signal processing may be possible.

Additionally, the provision of a sensor array comprising a plurality ofsensor devices may lead to an increasing parallelization of sensing oranalyzing the fluidic sample. Optionally, the sensor device or sensorarray may be arranged on or in a substrate which may form support forthe sensor device or sensor array and/or which may also support orimplement integrated circuitry adapted to perform some of themeasurements or processing of the signals induced or caused by thepassing fluidic sample.

Next, further exemplary embodiments of the sensor device will beexplained. However, these embodiments also apply to the sensor array andto the method of manufacturing a stacked sensing arrangement for thesensor device.

According to an exemplary embodiment of the sensor device the stackedsensing arrangement is formed by a stack of sensing layers.

Thus, the term “stack of sensing layers” may particularly denote anarrangement of at least three sensing layers, wherein the sensing layersare arranged above each other and having a dielectric layer arranged inbetween electrically insulating sensing layers so that a capacity orcapacitor may be formed by two sensing layers, The term “above of eachother” may particularly denote that the stack of sensing layers may havea quasi two-dimensional extension. All of the sensing layers may havethe same size or may have different sizes.

A sensing layer may be a part of several capacitors, for example it maybe form a capacitor with the sensing layer just above and a capacitorwith the sensing layer just below.

By providing a sensor device comprising a stack of sensing layer it maybe possible to perform multiple measurements for one and the samefluidic sample or analyt passing the plurality of capacities. Formeasuring a signal associated with the passing of the fluidic sample avoltage change in the sensing layers, an impedance measurement betweentwo sensing layers and/or a current due to tunnelling or resonanttunnelling between two sensing layers may be measured. Furthermore, theuse of a stack of sensing layers may enable the possibility to arrangethe sensing layer close to each other so that a good resolution may beachieved with respect to the different components of the fluidic sample.In particular, an arrangement of the sensing layers may be enabled whichprovide the possibility that a sequential “reading” or analysis of thefluidic sample may be performed. For example, it may be possible to evendistinguish different DNA bases of a DNA strand, when the DNA strandpasses through the hole and thus through the stacked sensingarrangement.

According to an exemplary embodiment of the sensor device the stack ofsensing layers comprises at least three sensing layers which arearranged above of each other and which are electrically insulated fromeach other by a dielectric layer arranged between the sensing layers. Inparticular, the stack of sensing layers may be planar, i.e. a layeredstructure having substantially a two dimensional extension, i.e. havingrelatively large directions in two dimensions while in the thirddimension, e.g. the thickness, the extension is small compared to theother two dimensions, e.g. the thickness may be less than the a tenth oreven less than one percent of the extensions of the width and/or thelength of the stack of sensing layers.

According to an exemplary embodiment of the sensor device the sensinglayers have a thickness of less than 10 nm. In particular, the thicknessmay be less than 5 nm or even less than 2 nm. Preferably, the thicknessmay be less than 1 nm, e.g. in the range between 0.1 nm and 0.5 nm.

According to an exemplary embodiment of the sensor device the thicknessof the dielectric layer is less than 10 nm. In particular, the thicknessof the dielectric layer may be less than 5 nm or even less than 3 nm.Preferably, the thickness or the dielectric layer may be less than 1 nm.

By providing sensing layers and/or dielectric layer between sensinglayers of different layers having such a small thickness it may bepossible to analyze or distinguish very small or short components, partsor portions in the fluidic sample or of particles in the fluidic sample.For example, in case the fluidic sample comprises a DNA strand it may bepossible that even single bases may be distinguished from each other.

According to an exemplary embodiment of the sensor device the thicknessof the dielectric layer is less than 10 nm. In particular, the thicknessof the dielectric layer may be less than 5 nm or even less than 3 nm.Preferably, the thickness or the dielectric layer may be less than 1 nm.

According to an exemplary embodiment the sensor device further comprisesan integrated circuit arrangement coupled to the sensing layers of thestacked sensing arrangement.

In particular, the integrated circuit arrangement may be included in themultilayer structure or may be formed as a part of the multilayerstructure. For example, the integrated circuit arrangement may compriseelectronic components like transistors, memories, processors, or thelike, which may be implemented by known semiconductor technologies, e.g.by CMOS technology. The integrated circuit arrangement may form part ofa detection system for detecting components of the fluidic sample oranalyt and may even include processors or part thereof for processingthe signals sensed by using the stacked sensing arrangement.Furthermore, the integrated circuit arrangement may include someamplifier which may also be formed in CMOS technology and which may beadapted to provide amplification for the signals provided by the stackedsensing arrangement.

According to an exemplary embodiment of the sensor device at least oneof the sensing layers is adapted to actuate the fluidic sample.

Next, further exemplary embodiments of the method of manufacturing astacked sensing arrangement for a sensor device sensor device will beexplained. However, these embodiments also apply to the sensor deviceand to the sensor array.

According to an exemplary embodiment of the method the multilayerstructure comprises a cover layer covering the stacked sensingarrangement. In particular, the cover layer may comprise a plurality ofsublayers, which may be formed by dielectric material, e.g. siliconnitride or silicon oxide.

According to an exemplary embodiment the method further comprisesforming a primary hole trough the cover layer, wherein the primary holehas a first size. In particular, the primary hole may be formed by usinglithographic techniques, and etching processes. According to anexemplary embodiment the method further comprises narrowing the primaryhole by forming a spacer arrangement on sidewalls of the primary hole.

By narrowing the primary hole a hole having a second size may be formedwherein the second size is smaller than the first size. This narrowingmay be performed by any known deposition step, e.g. by chemical vapourdeposition or the like. By such a narrowing it may be possible to form ahole having a smaller size, diameter or dimension than it is possible toachieve by standard lithography techniques since the deposition step maybe a suitable method to form layers of precise thickness, which may beused as spacers so that an accurate dimension of the primary hole may beadjustable. Since deposition techniques are well known and precise itmay thus be possible to form very small holes or nanopores. Inparticular, the size, diameter or width of the unnarrowed hole may be inthe range of 20 nm or even more than 20 nm while the size of thenarrowed hole may be in the range between 1 nm and 10 nm, or even below.To provide holes or nanopores having a such a small diameter may beadvantageous for fluidic samples including small particles or the like,e.g. DNA strands, since less other material of the fluidic sample may bepresent in the sensing area of the sensing layers, so that a shieldingeffect of the other material may be reduced. In particular, in case ofDNA strands the small dimension of the nanopore may also lead to astretching of the DNA strand so that an improved measurement may bepossible.

The term “spacer” may particularly denote a layer or a structure formedmainly in the vertical direction on another structure. It may be formedby isotropic deposition of material on a vertical structure. It may beused to increase the horizontal dimension of a multilayer structuresurrounding a hole and therefore narrowing the hole.

The technique of narrowing the hole with spacer may be an advantage toetch through a multilayer structure comprising a large number of layers.

According to an exemplary embodiment of the method the hole in thestacked sensing arrangement is formed by utilizing the primary hole. Inparticular, the narrowed primary hole may be used, e.g. the primary holemay be used as an etching mask. Thus, a small hole may be achievable byusing the primary hole or the narrowed primary hole as an etching mask.

According to an exemplary embodiment of the method the multilayerstructure is provided on a substrate. In particular, the substrate mayinclude an integrated circuit arrangement which may be formed bystandard semiconductor technologies or processing, e.g. CMOS technology.The formation or manufacturing of the substrate may form a part of thedescribed exemplary embodiment of the invention or the substrate may bea pre-fabricated or standard substrate which may be provided by asupplier.

According to an exemplary embodiment the method further comprisesforming contact terminals adapted to contact the stacked sensingarrangement.

According to an exemplary embodiment the method further comprisesintegrating electronic elements in the multilayer structure.

Summarizing according to a specific exemplary aspect a sensor device orsensor arrangement may be provided which comprises a plurality of stackof sensing layers of at least three sensing layers, each combinedstacked sensing arrangement with one hole through which a fluidic sampleor analyt may pass. The hole may also be called a nanopore. The stack ofsensing layers may be formed on or in a substrate and the plurality ofholes may be through holes (or through drilling or clearance holes orvia holes). Thus, a plurality of through holes may be formed to extendthrough the entire substrate which through holes may comprise side wallsbut may be free of a closed bottom. Each of the plurality of stack ofsensing layers may be used to measure an electric signal indicative forthe fluidic sample or at least a portion or part of the fluidic samplepassing through the respective hole at that point in time. The sensinglayers may have a small thickness, i.e. may be thin, so that componentsof the fluidic example may be distinguishable with good resolution. Forexample, the fluidic sample may comprise DNA strands which are analysedby the sensor devices or a sensor array comprising a plurality of sensordevices, while the fluidic sample flews through the holes of the sensorarray. In case the distance between the different sensing layers of eachstack of sensing layers is small enough it may be possible to identifythe sequence of the DNA bases. However, the multiple measurements andthus the redundancy of measurements during the passing of the fluidicsample through the whole stacked sensing arrangement may at leastimprove the achievable resolution of the analysis. In this context itshould be noted that this redundancy of measurements may not only beachievable by using at least three sensing layers based on the samedetection principle but may also be achievable by using a stackedsensing arrangement, in which several layers of sensing elements orsensing units based on different detection principles electric, magneticor optic principles. Each of the sensing layers may be adapted tomeasure a characteristic which may be evaluated by a respectiveprocessing element. Such a processing element may already formed in oron the substrate and may perform a complete processing or may perform apre-processing the result of which may be transmitted to an externalentity, e.g. an external processor or CPU of a computing device. For thetransmission a communication interface may be provided, particularly aUniversal Serial Bus (USB) interface, electrically coupled to thesensing layers or to a processing element. Thus, signal may be suppliedto a coupled entity such as a communication partner device. Such acommunication partner device may be a computer (such as a laptop) atwhich the measurements may be further evaluated. In an alternativeembodiment, the sensor array may be completely self-sufficient so thatno coupling with an external entity is necessary. However, in anembodiment in which a communication interface is present, the coupledentity such as a personal computer may further process the measurementsand/or display them to a user via a GUI (Graphical User Interface). Thecommunication between the sensor array and the communication partnerdevice may be a wired connection (such as in an embodiment with a USBinterface), or may be a wireless communication (for instance usingBluetooth, infrared communication or radio frequency communication).

For any method step, any conventional procedure as known fromsemiconductor technology may be implemented. Forming layers orcomponents may include deposition techniques like CVD (chemical vapourdeposition), PECVD (plasma enhanced chemical vapour deposition), ALD(atomic layer deposition), or sputtering. Polishing may include CMP(chemical mechanical polishing). Removing layers or components mayinclude etching techniques like wet etching, plasma etching, etc., aswell as patterning techniques like optical lithography, UV lithography,electron beam lithography, etc.

Embodiments of the invention are not bound to specific materials, sothat many different materials may be used. For conductive structures, itmay be possible to use metallization structures, silicide structures orpolysilicon structures. For semiconductor regions or components,crystalline silicon may be used. For insulating portions, silicon oxideor silicon nitride may be used.

Any process technologies like CMOS, BIPOLAR, BICMOS may be implemented.

The aspects defined above and further aspects of the invention areapparent from the examples of embodiment to be described hereinafter andare explained with reference to these examples of embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in more detail hereinafter withreference to examples of embodiment but to which the invention is notlimited.

FIG. 1 schematically illustrates a stacked sensing arrangement.

FIG. 2A to 2D schematically illustrates a method of manufacturing asensor device, in particular of a nanopore of the sensor device.

FIG. 3A to 3B schematically illustrates a first method of connecting asensor device.

FIG. 4A to 4J schematically illustrates a second method of connecting asensor device.

FIG. 5A to 5H schematically illustrates a third method of connecting asensor device.

DESCRIPTION OF EMBODIMENTS

The illustration in the drawing is schematical. In different drawings,similar or identical elements are provided with the same or similarreference signs.

FIG. 1 schematically illustrates a stacked sensing arrangement 100comprising four sensing layers 101, 102, 103, and 104 which areinsulated from each other, e.g. by a dielectric layer, e.g. a siliconoxide layer 105. The insulation may be formed by a single layer or maybe formed by several independent layers or sublayers. In particular, allsublayers or the whole insulation may be formed of or may at leastcomprise a same material, e.g. silicon oxide. Furthermore, the stackedsensing arrangement 100 comprises a hole or nanopore 106, which passesthrough all of the sensing layers and the dielectric layer, i.e. mayform a through hole 106. Therefore, a fluidic sample, e.g. a fluidcomprising particles like DNA strands, which is schematically indicatedby the respective bases marked with the letters depicted in FIG. 1, mayflow through the nanopore while passing the stacked sensing arrangement100. The stack of sensing layers may be formed by known lithographictechniques which will be described in more detail with respect to FIG.2. When the fluidic sample passes through the stack of sensing layers achange of electrical characteristics of the sensing layers may form asignal which may be transmitted from the sensing layers to an electriccircuitry, wherein the signal may depend on the bases just passing therespective sensing layers.

In the following, referring to FIG. 2, a method of manufacturing asensor device, in particular of a nanopore of the sensor device isdescribed. FIG. 2A shows a multilayer structure 200 comprising asubstrate 201 on which a stack of sensing layers 202 is formedcomprising four sensing layers 203, 204, 205, and 206 which are formedby electrical conductive material, e.g. TaN, Cu, Al or the like. Thesensing layers may have different sizes or extension in the width andlength dimension, so that each single layer may be contacted from above(in the coordinate system of FIG. 2) without interfering with eachother. The sensing layers are separated by a dielectric layer 207.Preferably, the material of the dielectric layer 207 is one which has alow probability to trap charges, e.g. silicon oxide. On top of the stackof sensing layers 202 a further dielectric layer 208 is formed which maybe used afterwards a stopping layer, e.g. for an etching process. Thestopping layer 208 may comprise silicon nitride. On top of the stoppinglayer a cover layer 209 is formed which may comprise several sublayers210, 211, 212 as shown in FIG. 2A and which may be formed of or at leastcomprising different dielectric materials, e.g. silicon oxide andsilicon nitride. The dielectric layer 208 is preferentially made ofsilicon nitride. The dielectric layer 210 is preferentially made ofsilicon oxide. The dielectric layer 211 is preferentially made ofsilicon nitride. The dielectric layer 212 is preferentially made ofsilicon oxide.

For forming the different layers of the multilayer structure 200 knowndeposition, lithography and etching techniques may be used. Preferably,the thickness of the sensing layers and the dielectric layer 207 inbetween are as thin as possible, in order to achieve an improvedresolution with respect to the fluidic sample, e.g. to differentiatedifferent base pairs of a DNA strand.

FIG. 2B schematically shows the multilayer structure 200 of FIG. 2Aafter a primary hole is formed in the cover layer 209 which is thenpartially filled by a spacer layer 214, in order to achieve a holehaving a small size or diameter. Thus, preferably the etching isperformed by an etching process already enable a minimal size of theetched hole. The etching may use the stopping layer 208 as an etch stop.Furthermore, the spacer layer 214 or the spacer reduces the size of theprimary hole and narrows the same. The spacer layer may be formed byisotropic deposition a dielectric material, e.g. silicon nitride.

FIG. 2C schematically shows the multilayer structure of FIG. 2B afterpartially removing the spacer layer 214 in order to form spacer in theprimary hole. Preferably, the etching is a selective etching, e.g. byusing a selective etching agent. For example, in case the spacer layeris formed by silicon nitride the etching agent may etch silicon nitridewell but may etch silicon oxide only to a small extend. This etchingstep may be particularly performed in order to remove the stopping layer207 on the bottom of the primary hole.

FIG. 2D schematically shows the multilayer structure 200 of FIG. 2Cafter a further etching step which is performed to etch a hole ornanopore 299 into the stack of sensing layers 202. Thus, an etchingagent may be used which is as much as possible selective with respect tosilicon nitride, i.e. may etch silicon oxide well but etch siliconnitride only to a small extend, in order to save some of the spacer 214.However, in case the spacers are formed of another material the etchingagent is preferably selective with respect to this material. The etchingstep uncovers the portions of the substrate 201 on the bottom of theformed nanopore 299.

In the following, referring to FIG. 3, a first method of connecting amultilayer structure or a sensor device, which may be formed by theprocess described with respect to FIG. 2, is described. In a first stepvias 315, 316, 317, and 318 are formed to uncover portions of thesensing layers 203, 204, 205, and 206, respectively. For the via formingstep a further etching step may be performed which may include thedeposition and patterning of a photoresist layer 319. Since the sensinglayers have different extensions in the lateral dimension in FIG. 3 itis possible to contact each sensing layer independently as shown in FIG.3. Alternatively, to forming the sensing layers so that they havedifferent extensions additionally conductive lines may be included inthe multilayer structure enlarging the dimensions of the sensing layers.In FIG. 3A the conductive lines are not shown since they are only anextension of the sensing layers. The conductive layers may be formed byCu or Al.

FIG. 3B shows the multilayer structure of FIG. 3B after a deposition ofthe vias are filled with conductive material, e.g. Al, so that contactlines 320 are formed. Afterwards the photoresist 319 is stripped leavingcontact or bond pads of the conductive material. Afterwards, thesubstrate is removed, e.g. by backgrinding and/or chemical etching.

The connecting method described in the context of FIG. 3 may beparticular suitable in case the sensing layers have a thickness whichensures that the conductance is high enough that no voltage drop occursin the sensing layers.

In the following, referring to FIG. 4, a second method of connecting amultilayer structure or a sensor device, which may be formed by theprocess described with respect to FIG. 2, is described. For clarityreasons only some of the reference signs which are already discussed anddescribed in context to FIG. 2 are shown in FIG. 4. A sacrificial layer430 and an optional hardmask 431 is deposited on top of the multilayerstructure of FIG. 2 for further processing. Possible materials for thesacrificial may be a polymeric material or polysilicon. The sacrificiallayer and the optional hardmask are then patterned, e.g. by etching, insuch a way that the hole is filled and covered by the sacrificial layerand the hardmask.

FIG. 4B shows the multilayer structure of FIG. 4A after deposition of atop layer 432, which may be formed by a dielectric material, e.g.silicon oxide. The top surface of the top layer 432 may then beplanarized, e.g. by chemical mechanical polishing (CMP).

FIG. 4C shows the multilayer structure of FIG. 4B after a furtheretching step to form vias 415, 416, 417, and 418 which may be used tocontact the sensing layers by contact lines 420, which may be formed byplugs of metallic material, e.g. Cu, W or other suitable materials. Forthe respective etching step the sensing layers, which may be formed byTaN, may be function as stopping layers. After the deposition of thecontact lines the surface may be planarized again, e.g. by CMP, in orderto planarized the plug material.

FIG. 4D and FIG. 4E show the multilayer structure of FIG. 4C after someoptional further processing steps for forming additional metal levels ormetal layers 440 (e.g. Cu), dielectric layers 441 (e.g. silicon oxide),bond pads 442 (e.g. Al), and passivation layers 443 (e.g. siliconnitride), and the like by using deposition steps, etching steps and/orCMP steps. In FIG. 4E only the bond pads for two sensing layers areshown for the sake of clarity. Additionally, the bond pads for thesensing layers may be formed on different levels or planes.

FIG. 4F shows the multilayer structure of FIG. 4E in a top view.Additionally, some dimensions of the different elements are shown.However, it must be clearly stated that the dimensions are not limitedto the given numbers but may be adapted to the specific needs. Inparticular, the dimensions of the bond pads 442 are shown which may havea rectangular or square cross section and a size of about 20 micrometerto 35 micrometer. Furthermore, the four vias 415, 416, 417, and 418 canbe seen in FIG. 4F and may have a size of about 130 nm and a distance ofabout 150 nm to 2 micrometer from each other. Moreover, the fillednanopore 299 formed in the multilayer structure.

FIG. 4G shows the multilayer structure of FIG. 4E after an additionaletching step performed in order to uncover the sacrificial layer 430 orthe hardmask 431 by patterning the passivation layer 443 and thedielectric layer 441. Preferably an etching agent may be used which isselective with respect to the material of the sacrificial layer 430,i.e. which ensures that the sacrificial layer 430 is not etched or atleast only etched to a small extend.

FIG. 4H shows the multilayer structure of FIG. 4G after an additionaletching step which is performed in order to remove the sacrificial layer430. In this case the agent may be selected that only or at leastprimarily the sacrificial layer 430 is removed, so that the substrate,e.g. a silicon wafer, is uncovered in the area of the nanopore 299.Afterwards the substrate is processed to remove it at least partially.This processing may be performed by backgrinding or etching.

FIG. 4I shows the multilayer structure of FIG. 4H in a top view. TheFIG. 4I differs from FIG. 4F mainly in the fact that the nanopore 299 isnot filled with the sacrificial layer any more.

FIG. 4J shows the multilayer structure of FIG. 4I in another alternativearrangement. In particular, the sensing layers are formed in a way thateach sensing layer extends mainly in a different direction. For example,in the case of FIG. 4 showing a stack of sensing layers comprising foursensing layers, the sensing layers may extend substantially indirections differing by an angle of 90°. Such an arrangement may enablethe use of shorter sensing layers which may improve a measurementperformed by using the sensing layers, e.g. by reduce parasiticcapacities and resistance of the stack of sensing layers and themultilayer structure.

In the following, referring to FIG. 5, a third method of connecting amultilayer structure or a sensor device, which may be formed by theprocess described with respect to FIG. 2, is described. FIG. 5A shows asubstrate 500 onto which integrated circuitry is formed which isdepicted only schematically in FIG. 5 by the layer 501. The integratedcircuitry may be formed by using known or standard techniques, e.g. CMOSand may form an integrated chip. A specific area 502 of the substratemay comprise no structure of integrated circuitry. In this areaafterwards a nanopore of a sensor device may be formed. On top of thelayer 501 some bond pads 503 are indicated in FIG. 5A which may beformed by conductive material, e.g. Al. Furthermore, FIG. 5A shows anencapsulation layer 504 which is formed by a dielectric material, e.g.silicon nitride. Above the bond pads 503 the encapsulation may beremoved in order to uncover the bond pads. The integrated chip may be astandard chip and may be commercially available or may be manufacturedaccording to specific needs.

FIG. 5B shows the multilayer structure of FIG. 5A after some furtherprocessing steps, in which a dielectric layer 505, e.g. silicon oxide,is formed on the structure which is afterwards planarized, e.g. by CMP.Further, a etch stop layer 506 is deposited on the dielectric layer 505which may be patterned afterwards to provide access to at least some ofthe bond pads 503, so that the uncovered bond pads may be contacted by ametal level or layer 507 which may be formed by a metallic layer, e.g. aCu layer.

FIG. 5C shows the multilayer structure of FIG. 5B after some furtherprocessing steps, in which a further dielectric layer 508, e.g. siliconoxide, is deposited on top of the etch stop layer 506 and is afterwardspatterned in order to uncover at least some portions of the metal level507 again by forming recesses 509. It should be noted that with respectto FIG. 5C to FIG. 5H a method of forming a stack of sensing layers isdescribed which is slightly different in the steps as the methoddescribed with respect to FIG. 2A to FIG. 2D.

FIG. 5D shows the multilayer structure of FIG. 5C after some furtherprocessing steps, in which a layer 510 of conductive material isdeposited on top of the dielectric layer 508 and the recesses 509,wherein the conductive material may be TaN, for example. The layer 510may be a first sensing layer. The conductive layer 510 may then beplanarized, e.g. by CMP, and may afterwards be patterned, in order toonly leaving areas covered or filled with the conductive material, whichare formed into sensing layers or contact areas for sensing layersafterwards. In particular, the conductive layer 510 may remain inregions of the metal layer 507 or in areas above the unstructured areas502 of the integrated chip 501.

FIG. 5E shows the multilayer structure of FIG. 5D after some furtherprocessing steps, in which a further dielectric layer 511 is depositedcomprising silicon oxide, for example to cover the conductive layer 510and to provide an insulating layer with respect to a further sensinglayer. The dielectric layer 511 may then be patterned, e.g. etched, inorder to uncover portions of the conductive layer 510 again, in order toenable the contacting of the first sensing layer. The uncovered portionsmay in particular correspond to the areas where the recesses 509 whereformed and filled with the conductive layer, i.e. in regions which arearranged above the metal level 507.

FIG. 5F shows the multilayer structure of FIG. 5E after a furtherdeposition step in which a further metal layer 512 is formed which aftersome patterning may form a second sensing layer and a contact area ofthe same. The metal layer 512 is afterwards planarized, e.g. CMP, etchedin a similar way as described with respect to FIG. 5D, i.e. to form thesecond sensing layer above the unstructured area 502 and to provide acontact to the same. After the patterning step a dielectric coveringlayer 513 is formed.

Further steps as described with respect to FIG. 5D and FIG. 5E may berepeated in order to provide more than two sensing layers. For the sakeof clarity of this description and the FIG. 5 the number of sensinglayers is restricted to two.

With respect to FIG. 5G the creation of a nanopore 299 is shown.However, as the forming of the nanopore is similar to the process asdescribed in context to FIG. 2 a detailed description is omitted. Ingeneral, a dielectric cover layer is formed on the structure shown inFIG. 5F and a primary hole is formed above the unstructured area 502.Afterwards a narrowing layer 214, e.g. comprising silicon nitride, isformed on and in the primary hole. Then the stack of sensing layer ispatterned, e.g. etched, by using the spacer formed by the narrowinglayer as a mask, wherein the patterning is stopped at the etch stoplayer 506. This patterning forms the nanopore in the region of the stackof sensing layers.

With respect to FIG. 5H a bond pad opening is shown, i.e. a patterninguncovering at least some of the of the bond pads 503 in order to contactthem by a conductive layer 514. This opening may be done by an etchingstep as well. If necessary, the nanopore may be protected during thisetching step by a protection layer, e.g. by a sacrificial layer, if anadditional metal layer is needed on top, or a lift off technique isused. However, the additional metal layer may also stay like this, i.e.projecting as depicted in FIG. 5H, since the difference in height 515between the bond pads and the top layer may only be a few micrometerwhich may not cause any problems. Another solution may be to make thecontacts from the backside after a backgrinding.

With respect to FIG. 5I further steps of opening the nanopore, i.e. toprovide a through hole are described. In a first step a backgrinding ofthe substrate 500 is performed which is followed by a patterning step ofthe unstructured area 502. In this patterning step, e.g. etching step,the unstructured area is removed as well as the encapsulation layer 504and the dielectric layer 505 in this area. The etch stop layer 506 mayperform as an etch stop in this etching step. Afterwards the etch stoplayer is removed in the area to open the nanopore so that a channelthrough the structure shown in FIG. 5 for a fluidic sample is provided.Additionally, some exemplary dimensions are given in FIG. 5I as well. Inparticular, the cross sectional size of the nanopore in the area of thestack of sensing layers is in the order of 5 nm while the channelthrough the substrate and the integrated circuitry level 501 may be inthe range of 5 micrometer. The lateral size of the bond pads may be inthe range of 35 micrometer, while the distance between bond pads may bein the range of 100 micrometer. The thickness of the dielectric layer505 may be in the range of 3 micrometer, while the thickness of theintegrated chip 501 may be in the range of 10 micrometer. The thicknessof the multilayer structure 550 may be in the range of 1 micrometer,while the lateral extension of each sensing layer may be in the range of1 micrometer. Additionally, the width of the contact lines contactingthe bond pads may be in the range of 33 micrometer. However, it shouldbe stressed that these numbers are just exemplary dimensions which maybe altered in a wide range according to the specific needs. In analternative embodiment, the contact to the bond pads may be done at thebackside instead of the front side, for example by through silicon viatechniques.

It should be noted that although two sensing layers are described withrespect to the figures it is of course possible to use another number inparticular a greater number of sensing layers. Furthermore, it should benoted that a sensor array may be manufactured comprising a plurality ofstack of stack of sensing layers with corresponding holes or nanopores.Additionally, it is noted as well that of course other materials thanthe described are possible. Furthermore, it should be noted that thespecific materials stated in the above description are just exemplary,e.g. instead of TaN as the conductive material of the sensing layersevery other suitable conductive material can be used.

The above described sensor device comprising a stack of sensing layersmay be suitable to perform a detection or sampling based on voltagechanges in the sensing layers, tunneling current between two sensinglayers or resonant tunneling, or impedance measurement between twosensing layers. Since a small distance between two following sensinglayers is possible it may be possible to even identify or distinguishmonomers of a polymer which are very close together, like bases in a DNAstrand. Furthermore, the redundant measurement with the differentsensing layer may reduce an ambiguity which may arise out of the motionof the fluidic sample, since the moving velocity and/or the movingdirection of the fluidic sample may vary, which might, in case noredundancy due to several sensing layers is provided, lead to the factthat it is not clear whether the fluidic sample comprises several timesthe same monomer or whether the same monomer is measured several times.Additionally, it may be possible to improve a parallel processing, sinceit may be possible to provide arrays of stacked sensing arrangementswhich do not need separate off-chip electronic, like processing andamplification. In particular, some described embodiments may have thefollowing advantages:

the distance between sensing layers can be very small and very precisepossibly leading to a better distinction between the DNA bases,

a large number of sensing layers may be included,

possibility to etch a hole of a few nm in a relatively “high” layer,where several sensing layers or a detection system can be includedpossibly leading to a sequential reading, possibility to make an arrayinstead of a discrete device because a circuitry with several metallevels is possible possibly leading to an improved parallelism,

possibility of latter statistical and error-cancellation treatmentbecause the DNA will face several sensing layers one after each other ineach nanopore and several nanopores in parallel may screen several DNAstrands,

possibility to integrate CMOS so that on-chip amplification (for exampleby an integrated Sauty bridge) and on-chip signal processing may bepossible, and

conventional litho techniques may be used instead of e-beam, ion-beam orion-beam with sculpting.

Furthermore, it should be noted that preferably connection paths orconnection links to the sensing layers may be short and/or therespective connection points between a bond pad and the sensing layermay be arranged close to the nanopore so that it may be possible toreduce parasitic capacitance or high resistance of the stacked sensingarrangement. Finally, it should be noted that the above-mentionedembodiments illustrate rather than limit the invention, and that thoseskilled in the art will be capable of designing many alternativeembodiments without departing from the scope of the invention as definedby the appended claims. In the claims, any reference signs placed inparentheses shall not be construed as limiting the claims. The words“comprising” and “comprises”, and the like, do not exclude the presenceof elements or steps other than those listed in any claim or thespecification as a whole. The singular reference of an element does notexclude the plural reference of such elements and vice-versa. In adevice claim enumerating several means, several of these means may beembodied by one and the same item of software or hardware. The mere factthat certain measures are recited in mutually different dependent claimsdoes not indicate that a combination of these measures cannot be used toadvantage.

1. A sensor device for analyzing components of a fluidic sample, thesensor device comprising: a multilayer structure comprising: a nanoporeformed therein which is adapted to let pass the fluidic sample; astacked sensing arrangement arranged in such a way that the fluidicsample passes the stacked sensing arrangement when the fluidic samplepasses the nanopore, the stacked sensing arrangement comprising at leastthree sensing layers which are arranged above of each other and whichare electrically insulated from each other by a dielectric layerarranged between two sensing layers; and a cover layer over the stackedsensing arrangement having a primary hole over the nanopore, saidprimary hole comprising sidewall spacers
 2. (canceled)
 3. The sensordevice according to claim 1, wherein the sensing layers have a thicknessof less than 10 nm.
 4. The sensor device according to claim 1, whereinthe thickness of the dielectric layer is less than 10 nm.
 5. The sensordevice according to claim 1, further comprising: an integrated circuitarrangement coupled to the sensing layers of the stacked sensingarrangement.
 6. The sensor device according to claim 1, wherein at leastone of the sensing layers is adapted to actuate the fluidic sample.
 7. Asensor array for analyzing components of a fluidic sample, the sensorarray comprising: a plurality of sensor devices according to claim
 1. 8.A method of manufacturing a stacked sensing arrangement for a sensordevice for analyzing components of a fluidic sample, the methodcomprising: providing a multilayer structure comprising a stackedsensing arrangement, and a cover layer covering the stacked sensingarrangement, said stacked sensing arrangement comprising at least threesensing layers which are arranged above of each other and which areelectrically insulated from each other by a dielectric layer arrangedbetween two sensing layers, forming a primary hole through the coverlayer, wherein the primary hole has a first size; narrowing the primaryhole by forming a spacer arrangement on sidewalls of the primary hole;and forming a nanopore through the stacked sensing arrangement, whereinthe nanopore is adapted to let pass the fluidic sample.
 9. (canceled)10. (canceled)
 11. (canceled)
 12. (canceled)
 13. The method according toclaim 8, wherein the multilayer structure is provided on a substrate.14. The method according to claim 8 further comprising: forming contactterminals adapted to contact the stacked sensing arrangement.
 15. Themethod according to claim 8, further comprising: integrating electronicelements in the multilayer structure.